Alkaline Earth Metals

The elements of beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) and radium (Ra), constitute group 2 of the periodic table.

Occurrence

Magnesium

It occurs mainly as insoluble carbonates, sulphates and silicates, in crystal rocks. It is the sixth most abundant element following calcium. Magnesium occurs as dolomites (MgCO₃.CaCO₃), magnesites (MgCO₃), epsomite (MgSO₄.7H₂O). It is further represented by common basaltic mineral olivine [(MgFe)₂SiO₄] and by soapstone (talc) Mg₃Si₄O₁₀(OH₂) , etc., as silicates.

Calcium

It is fifth most abundant element in Earth's crust. It is found existing as whole mountain ranges of limestone, marble and chalk, in vast sedimentary rocks of CaCO₃. Other important minerals containing calcium are gypsum (CaSO₄.2H₂O), anhydrite (CaSO₄), fluorite (CaF₂) and fluorapatite [3Ca₃(PO₄)₂.CaF₂].

Strontium

It occurs as celestite (SrSO₄) and strontianite (SrCO₃).

Barium

The main ore of barium is baryte (BaSO₄). It also occurs as witherite (BaCO₃).

Beryllium

It is found as surface deposits of beryl in pegmatite rocks. Like Lithium it occurs in less abundance.

Radium

Radium occurs only in association with uranium, having a terrestrial abundance of approximately 10^-6ppm.